1. Field of the Invention
The present invention relates to an imaging device.
Priority is claimed on Japanese Patent Application No. 2012-281277, filed Dec. 25, 2012, the content of which is incorporated herein by reference.
2. Description of Related Art
A general imaging device such as a digital still camera or video camera includes an image-acquiring unit that acquires a pixel signal output from a solid-state imaging device and the remaining components. For example, an imaging device is configured such that an image-acquiring unit and the remaining components are connected to a dynamic random access memory (DRAM) that temporarily stores data via a data bus (see Japanese Unexamined Patent Application, First Publication No. 2010-199880A). Further, when photography is performed with the imaging device, the image-acquiring unit transfers image data according to a pixel signal acquired from a solid-state imaging device to the DRAM via the data bus and causes the image data to be stored (written) in the DRAM. Further, when photography is performed with the imaging device, the remaining components read the image data stored in the DRAM and respective corresponding processes.
Each of the image-acquiring unit and the remaining components equipped in the imaging device includes a direct memory access-interface (DMA-IF) used to exchange data with direct memory access (DMA). Each DMA-IF includes a memory such as a static random access memory (SRAM) as an internal data buffer.
In the past, imaging devices having a constitution in which a plurality of image-processing units that perform image processing on image data which has been acquired from a solid-state imaging device and then stored (written) in a DRAM by an image-acquiring unit are provided, and the image-processing units perform image processing in parallel have been put to practical use. In the imaging device including the plurality of image-processing units, as image data stored in the DRAM is simultaneously subjected to image processing, a function of simultaneously performing shooting of different types or different sizes (angles of view) is implemented. Examples of a function of simultaneously performing shooting of different types or different sizes (angles of view) include a function of shooting a still image while shooting a moving image and a function of shooting a wide-angle (wide) moving image and a telescopic (tele) moving image.
For example, an imaging device that simultaneously shoots a moving image and a still image includes a still image-processing unit and a moving image-processing unit. The still image-processing unit performs image processing on image data of an overall region to be imaged by the solid-state imaging device. The moving image-processing unit performs image processing on image data of a region smaller than that in the still image-processing unit.
Further, for example, an imaging device that simultaneously shoots a wide-angle image and a telescopic image includes a wide-angle image-processing unit and a telescopic image-processing unit. The wide-angle image-processing unit performs image processing on image data of an overall region to be imaged by the solid-state imaging device. Further, the telescopic image-processing unit performs image processing on image data of a telescopic region partially clipped from an overall region to be imaged by the solid-state imaging device.
Further, in recent years, solid-state imaging devices that simultaneously output a plurality of pixel signals, for example, pixel signals of two pixels adjacent in a horizontal direction or pixel signals of two pixels adjacent in a vertical direction, have been put to practical use.
Furthermore, an imaging device in which a plurality of image-processing units are provided to reduce a load of image processing to be performed on image data corresponding to a pixel signal acquired from a solid-state imaging device has been disclosed, for example, in Japanese Unexamined Patent Application, First Publication No. 2010-103935A. In the technique disclosed in “2010-103935A”, one of the image-processing units first sequentially reads accumulated image data and performs image processing while sequentially accumulating image data corresponding to one frame at the time of continuous shooting. Then, when the remaining capacity of the buffer memory is small, another image-processing unit is activated, and the two image-processing units alternately read image data stored in the buffer memory and perform image processing in parallel.